At present, the most widely and valid method for these patients is the Bilevel Positive Airway Pressure (BiPAP) ventilation, while, recently, the investigators discovered a completely novel device, namely auto-trilevel Ventilator. In contrast to the traditional therapy, auto-trilevel Ventilator has a more flexible expiratory positive airway pressure (EPAP), with which it can removing residual obstructive sleep apnea hypopnea events and correcting hypercapnia without contradiction. Treated with auto-trilevel ventilator may delay the progression of disease and improve life quality. The overall purpose of this study is to determine the curative effects of auto-trilevel ventilators on patients with OHS and OSAHS.